Generally, the color bar pattern means a test pattern which becomes a reference in the testing and adjusting of the color and luminance.
This color bar pattern is electrically generated and output instead of the video signal of the broadcasting equipment such as a camera. The color bar pattern generator, conventionally, is made up of a custom IC and is connected to a color coder of the camera for the broadcasting or business.
Of the existing color patterns in the broadcasting system of NTSC type, the color bar pattern which is being most widely used at present is the EIA color bar pattern under RS-189A in the EIA standards, which is shown in FIG. 1A.
In FIG. 1 the vertical lines show IRE units, while the horizontal lines show a horizontal scanning period.
The EIA color bar pattern is composed of a chroma set CS having 7 colors arranged in order of the luminance, and a black/white set BW in which the carrier signals Y, I and Q of the video signal are displayed.
In the standard EIA color bar pattern, the chroma set CS is displayed over 75% of the vertical effective period, Ev while the black/white set BW is displayed only over 25% thereof.
The chroma set CS is formed in such a manner that the vertical color bar of 75% white 75 W, yellow Y, cyan, green G, magenta M, red R, blue B is displayed with a width b corresponding to 1/7 of the width of the horizontal effective period Eh.
While, in the black/white set BW, I signal, 100% white 100 W and Q signal are each displayed with a width 5/4b, and black is displayed to the remaining width of the horizontal effective period Eh. The video outputs of this chroma set CS and black/white set BW are controlled by the horizontal and vertical control signals Ch and Cv of the horizontal and vertical blanking periods Bh and Bv, at this time, said horizontal and vertical control signals include for example, horizontal and vertical synchronizing signals or horizontal and vertical blanking pulses, etc.
The EIA color bar pattern shown in FIG. 1B is output with the same waveform as that shown in FIGS. 1A and 1C from the color bar pattern generator which is not shown.
In the chroma set CS, as shown in FIG. 1B, after a horizontal control signal Ch such as the horizontal synchronizing pulse is applied during the horizontal blanking period Bh, a chroma synchronizing signal or burst signal BS is supplied, and the vertical color bar is displayed during the horizontal effective period Eh in the above-mentioned order.
In the black/white set BW, the horizontal control signal Ch is applied thereto, then the burst signal BS is supplied, as shown in FIG. 1C, so that I, Q and black/white bars are displayed.
The difference between the lowest level of displayable black/white and O level of IRE unit of the input signal in the black/white set is called "set up".
At this time, since the burst signal BS is supplied commonly to the display of the chroma set CS and black/white set BW, color noise may be generated to the output of the black/white set BW.
To solve this problem, the EIA color generator outputs a separate color control signal to distinguish both outputs during display of the chroma set CS.
Thus, the EIA color bar generator outputs R,G,B signals displaying the colors, a chrominance signal of I,Q signals for carrying the color signal, a Y signal which indicates the luminance and is displayed by the black/white, and a chrominance control signal, at this time the chrominance control signal is output, for example during only 75% of the period of the vertical effective period Ev during output of the chroma set CS.
In the meanwhile, SMPTE have proposed a so-called "SMPTE color bar pattern".
This pattern is provided with a reversed chroma set RC in a portion of the chroma set CS of said pattern, and a pedestal set PED for displaying the set-up level in a portion of the black/white set BW.
In the pattern of the standard SMPTE color bar, the chroma set CS is displayed during a 67% period of the vertical effective period Ev, while the reversed chroma set RC is 8% and the black/white set Bw is only 25%, at this time the pedestal set PED is displayed by two parts, which are of a level-down portion PED 1 and a level-up portion PED 2 below magenta M and red R.
Such a SMPTE color bar pattern is easier in the testing and adjusting of the chrominance and luminance than the EIA color bar pattern, so that it is widely used gradually.
Therefore, it has a disadvantage that the broadcasting equipment provided with the EIA color bar pattern generator can not be used for generation of the SMPTE color bar pattern.